A class of relational databases has low degree if for all $\delta>0$, all but finitely many databases in the class have degree at most $n^{\delta}$, where $n$ is the size of the database. Typical examples are databases of bounded degree or of degree bounded by $\log n$. It is known that over a class of databases having low degree, first-order boolean queries can be checked in pseudo-linear time, i.e.\ for all $\epsilon>0$ in time bounded by $n^{1+\epsilon}$. We generalize this result by considering query evaluation. We show that counting the number of answers to a query can be done in pseudo-linear time and that after a pseudo-linear time preprocessing we can test in constant time whether a given tuple is a solution to a query or enumerate the answers to a query with constant delay.

@article{paperbot1703,
  title = {Enumerating Answers to First-Order Queries over Databases of Low Degree},
  author = {Arnaud Durand and Nicole Schweikardt and Luc Segoufin},
  journal = {Logical Methods in Computer Science},
  volume = {Volume 18, Issue 2},
  year = {2022},
  doi = {10.46298/lmcs-18(2:7)2022}
}